The mission of the Pediatric Early Phase Clinical Trials Network (PEP-CTN) is to identify and develop effective new agents for children and adolescents with cancer, through rational and efficient clinical and laboratory research. PEP-CTN clinical trials will incorporate correlative genomics, biology, pharmacology, and imaging studies to further the understanding of the disposition and action of new agents introduced into the treatment of children with cancer. Annually, the PEP-CTN will enroll approximately 120 children and adolescents with cancer onto clinical trials of novel anticancer agents at the 21 core premier pediatric oncology sites throughout the country. The network institutions are selected through a peer review process, and serve as a national and international model for new agent development in pediatric oncology. The PEP- CTN will leverage the database infrastructure and resources of the parent Children's Oncology Group while maintaining its own administrative and operational infrastructure to ensure rapid development, implementation, and reporting of specialized and complex early phase clinical trials. The PEP-CTN has expertise and resources for the conduct of translational biology, pharmacokinetic, and pharmacogenetic studies, and utilizes state-of-the-art informatics systems to facilitate the transfer of response and correlative imaging studies for central review and analyses. The PEP-CTN's primary specific aims are: 1) To safely and efficiently introduce novel anticancer agents into the pediatric setting through the conduct of early phase clinical trials; 2) To expeditiously obtain preliminary efficacy signals through use of phase 2 expansion cohorts and pilot studies in order to inform tumor specific trials that will be conducted across COG sites; 3) To perform genomic analyses, including single gene studies or gene panels, to identify appropriate patients for early phase studies of targeted agents; 4) To identify associations of tumor characteristics with response to new agents using genomic analyses such as whole exome sequencing and RNA sequencing; 5) To incorporate pharmacologic and biologic endpoints, including circulating tumor DNA, other translational laboratory studies, and imaging modalities, into early phase studies, in order to enhance our understanding of the new agents and their effect on tumors.. Development of targeted therapy for childhood cancer is a high priority as it offers the prospect of more efficacious and less toxic therapeutics.